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Mol. Cells 2013; 36(1): 88-96

Published online July 31, 2013

https://doi.org/10.1007/s10059-013-0097-7

© The Korean Society for Molecular and Cellular Biology

Genetic Identification of a Second Site Modifier of ctr1-1 that Controls Ethylene-Responsive and Gravitropic Root Growth in Arabidopsis thaliana

Kihye Shin Rin-A Lee, Inhye Lee, Sumin Lee, Soon Ki Park, and Moon-Soo Soh

1Department of Molecular Biology, College of Life Science, Sejong University, Seoul 143-747, Korea, 2School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Korea, 3These authors contributed equally to this work.

Received: March 26, 2013; Revised: May 2, 2013; Accepted: May 8, 2013

Abstract

Ethylene controls myriad aspects of plant growth throughout developmental stages in higher plants. It has been well established that ethylene-responsive growth entails extensive crosstalk with other plant hormones, particularly auxin. Here, we report a genetic mutation, named 1-aminocyclopropane carboxylic acid (ACC) resistant root1-1 (are1-1) in Arabidopsis thaliana (L.) Heynh. The CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) encodes a Raf-related protein, functioning as an upstream negative regulator of ethylene signaling in Arabidopsis thaliana. We found that the ctr1-1, a kinase-inactive allele exhibited slightly, but significantly, longer root length, compared to ACC-treated wild-type or ctr1-3, a null allele. Our genetic studies unveiled the existence of are1-1 mutation in the ctr1-1 mutant, as a secondsite modifier which confers root-specific ethylene-resistance. Based on well-characterized crosstalk between ethylene and auxin during ethylene-responsive root growth, we performed various physiological analyses. Whereas are1-1 displayed normal sensitivity to synthetic auxins, it showed modest resistance to an auxin transport inhibitor, 1-Nnaphthylphthalamic acid. In addition, are1-1 mutant exhibited ectopically altered DR5:GUS activity upon ethylenetreatment. The results implicated the involvement of are1-1 in auxin-distribution, but not in auxin-biosynthesis, -uptake, or -sensitivity. In agreement, are1-1 mutant exhibited reduced gravitropic root growth and defective redistribution of DR5:GUS activity upon gravi-stimulation. Taken together with genetic and molecular analysis, our results suggest that ARE1 defines a novel locus to control ethylene-responsive root growth as well as gravitropic root growth presumably through auxin distribution in Arabidopsis thaliana.

Keywords Arabidopsis, auxin, ctr1-1, ethylene, gravitropism

Article

Research Article

Mol. Cells 2013; 36(1): 88-96

Published online July 31, 2013 https://doi.org/10.1007/s10059-013-0097-7

Copyright © The Korean Society for Molecular and Cellular Biology.

Genetic Identification of a Second Site Modifier of ctr1-1 that Controls Ethylene-Responsive and Gravitropic Root Growth in Arabidopsis thaliana

Kihye Shin Rin-A Lee, Inhye Lee, Sumin Lee, Soon Ki Park, and Moon-Soo Soh

1Department of Molecular Biology, College of Life Science, Sejong University, Seoul 143-747, Korea, 2School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Korea, 3These authors contributed equally to this work.

Received: March 26, 2013; Revised: May 2, 2013; Accepted: May 8, 2013

Abstract

Ethylene controls myriad aspects of plant growth throughout developmental stages in higher plants. It has been well established that ethylene-responsive growth entails extensive crosstalk with other plant hormones, particularly auxin. Here, we report a genetic mutation, named 1-aminocyclopropane carboxylic acid (ACC) resistant root1-1 (are1-1) in Arabidopsis thaliana (L.) Heynh. The CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) encodes a Raf-related protein, functioning as an upstream negative regulator of ethylene signaling in Arabidopsis thaliana. We found that the ctr1-1, a kinase-inactive allele exhibited slightly, but significantly, longer root length, compared to ACC-treated wild-type or ctr1-3, a null allele. Our genetic studies unveiled the existence of are1-1 mutation in the ctr1-1 mutant, as a secondsite modifier which confers root-specific ethylene-resistance. Based on well-characterized crosstalk between ethylene and auxin during ethylene-responsive root growth, we performed various physiological analyses. Whereas are1-1 displayed normal sensitivity to synthetic auxins, it showed modest resistance to an auxin transport inhibitor, 1-Nnaphthylphthalamic acid. In addition, are1-1 mutant exhibited ectopically altered DR5:GUS activity upon ethylenetreatment. The results implicated the involvement of are1-1 in auxin-distribution, but not in auxin-biosynthesis, -uptake, or -sensitivity. In agreement, are1-1 mutant exhibited reduced gravitropic root growth and defective redistribution of DR5:GUS activity upon gravi-stimulation. Taken together with genetic and molecular analysis, our results suggest that ARE1 defines a novel locus to control ethylene-responsive root growth as well as gravitropic root growth presumably through auxin distribution in Arabidopsis thaliana.

Keywords: Arabidopsis, auxin, ctr1-1, ethylene, gravitropism

Mol. Cells
May 31, 2022 Vol.45 No.5, pp. 273~352
COVER PICTURE
Fe2+ ion depletion-induced expression of BΔGFP at the early stage of leaf development (Choi et al., pp. 294-305).

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